One of the major contributors to current worldwide generation of renewable energy is the solar energy produced via a photovoltaic (PV) effect. PV-based renewable-energy sources generate energy, in the form of electricity, by harnessing electromagnetic radiation, such as sunlight. PV applications are not limited to any particular area of the world and/or any given sector of economy. In remote regions of the world, for example, an off-grid installation of the PV source provides the only available source of electricity. In highly populated and/or economically developed regions, the PV source may, for example, source electricity to an electrical grid to supplement and/or reduce the amount of conventional energy distributed from the electrical grid. A PV source is in general any electric system containing a PV device, such as a PV cell or a PV module.
Most modern PV systems collect and aggregate all direct-current (DC) power from individual solar panels before converting it to the alternating-current (AC) form using a central inverter operating a line frequency of an AC grid. In another approach, each PV module may be equipped with a separate, independently controlled micro-inverter that produces AC power locally and thus can be directly connected to an AC grid. The main advantage of the central-inverter approach is its relatively lower cost; however, this approach has a lower energy yield. The main advantage of the micro-inverter approach is a higher energy yield, while its drawbacks include higher manufacturing costs.
The inventors believe that other PV system architectures are needed that could reduce overall system costs and at the same time enhance performance, safety and reliability. Furthermore, different system approaches are also needed in order to ensure that the solar and other renewable technologies can be integrated into the grid at high penetrations and in a safe and reliable manner. Such approaches would require alternative system architectures and power electronics topologies, which will provide not only an attractive combination of benefits of legacy systems, but also new and advanced functionalities addressing issues related to the interconnection between a PV system and a utility grid.